Abstract: Polysaccharide was extracted from Ginkgo biloba fallen leaves by ultrasound-assisted water extraction and alcohol precipitation. The extraction technology was preliminarily studied by single factor and response surface method.The results showed that the optimum extraction conditions were as follows:G. biloba fallen leaves 5.0 g, ultrasound power 600 W, liquid/solid ratio 40:1(mL:g), extraction temperature 84 ℃, extraction time 50 min, the final polysaccharide yield was 6.61 %. Because this study was only a preliminary study on the extraction process of polysaccharides from the leaves of Ginkgo biloba, the extraction principle of "small amount of times and total liquid ratio is less" was not considered.

Key words: Ginkgo biloba fallen leaves, polysaccharide, ultrasonic extraction, response surface method